Patent GB-736078-A (GB)
Title: Improvements in or relating to gaseous electric discharge tubes and circuit arrangements therefor
IPC: G06F7/498
Filed: 1952-05-08
Abstract: 736,078. Electronic counting apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 8, 1952 [May 15, 1951], No. 11641/52. Class 106(1). [Also in Group XL (a)] A counting arrangement for storing both positive and negative quantities comprises a cold-cathode gas-filled tube 10 of the type described in Specification 720,179 having ten transfer cathodes C-O to C-9 connected in common to an input terminal 12 and ten position cathodes Cp-0 to Cp-9 arranged alternately with the transfer cathodes and connected in common to a terminal 11 to which a positive voltage is applied over a lead 11a, glow transfer wires gt being positioned between adjacent cathodes. A glow discharge existing between any position cathode and the common anode A is stepped to successive position cathodes by applying negative pulses to the transfer cathodes by way of terminal 12. The present tube comprises an additional group of holding cathodes Cs-0 to Cs-9, each associated with one of the position cathodes Cp-0 to Cp-9, two glow transfer wires gt being provided between each holding cathode and its associated position cathode. The cathodes are all in the form of hollow cylinders coated with some suitable material so that a glow discharge is confined to the inner surface. The holding cathodes are connected in common by a lead 15 to a trigger circuit 16 including a vacuum tube 17 having two triode sections L and R the anodes of which are connected to a positive supply terminal 18 and the grids to negative supply terminals 19 and an input terminal 20. The trigger circuit is designed to initially assume the LEFT condition, i.e. the condition in which section L is conductive and section R is non- conductive so that the voltage at the anode of section R is high. If a negative pulse is applied to terminal 20 the trigger circuit changes over to the RIGHT condition, in which the voltage at the anode of section R is low. These high or low voltages are applied by way of lead 15 to the holding cathodes of tube 10. If a high voltage is applied, a glow discharge existing at a position cathode remains at that cathode or if existing at a holding cathode is transferred to the corresponding position cathode. If a low voltage is applied, a discharge existing at a position cathode is transferred to the corresponding holding cathode, or if existing at a holding cathode, remains at that cathode. The arrangement is operated by a plurality of pulses, Fig. 2, produced by any conventionl means. The Specification describes a circuit controlled by a record card having fourteen index points per card cycle. Clock or timed pulses are provided intermediate successive index points from points 0 to 9 as shown. A card pulse is produced at any index point X to 9. A reset pulse is produced at point 13 and a carry pulse at point 14. Index point D represents the point where one card cycle ends and the next one begins. Assuming a discharge at position cathode Cp-0, the trigger circuit 16 being in the LEFT condition, the storage of a positive quantity, e.g. + 2, is begun by the application of clock pulses to the input terminal 12. The pulses step the discharge to position cathode Cp-2 whereupon a card pulse applied to input terminal 20 causes the trigger circuit to change over to the RIGHT condition and the discharge is transferred to holding cathode Cs-2 and subsequent clock pulses during the remaining portion of the card cycle have no effect on the position of the discharge. Finally at 13 time a reset pulse R switches the trigger circuit to the LEFT condition and the discharge is transferred back to position cathode Cp-2. Next, the carry pulse C is applied to a carry circuit if a plurality of tubes is used as an accumulator. Read-out may now be effected, for example by stepping the discharge through ten counts. The storage of a negative quantity, e.g. - 2, is accomplished by storing the 9's complement of the quantity, the fact that the quantity is negative being indicated by a pulse S at the X position which switches the trigger circuit to the RIGHT condition so that an initial discharge at position cathode Cp-0 is transferred to the holding cathode Cs-0 and remains there until card pulse 2C effects the transfer of the discharge back to position cathode Cp-0. The seven subsequent clock pulses then step the discharge to position cathode Cp-7 thereby storing the - 2 as + 7, the 9's complement of the negative quantity.